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Mathew Rosengart, recognized as one of the “nation’s preeminent” and “foremost” litigators, is a former federal prosecutor, previously serving as a Supervisory Assistant United States Attorney and Justice Department Trial Attorney. A Governor of the Beverly Hills Bar Association and former law clerk to Justice David Souter on the New Hampshire Supreme Court, Mathew has been recognized as a California Lawyer Attorney of the Year and one of the Top 100 lawyers in the State by the Daily Journal; a Sports & Entertainment Law Trailblazer by The National Law Journal; Lawyer of the Year by Above the Law; Litigator of the Week by The American Lawyer; Lawyer of the Week by Original Jurisdiction; a Top 100 Lawyer by the Los Angeles Business Journal; an LA500 Visionary Leader; and Leader of Influence and Top Litigator & Trial Attorney by the LA Business Journal, which honors “masters of their craft” who “go to the proverbial mat to fight for their clients.” The issue recognized Mathew as “one of the most influential litigators” in Los Angeles and a “go to litigator for Hollywood’s elite and Corporate America” who is “one of the nation’s preeminent litigators.”

Described by the New York Times as a “prominent” and “high-powered lawyer,” Mathew has also been lauded as a “legal powerhouse,” a “powerful litigator,” a “legal warrior” who is “principled,” and a “heavyweight lawyer” by Yahoo News, Newsweek, The View, Good Morning America, and The Guardian. He has also been recognized by NPR as a lawyer with “a lot of star power,” by Los Angeles Magazine as a “heavy hitter” with “a long history of getting results for his big name clients,” and by The Wall Street Journal, The Hollywood Reporter, and NBC’s Today as a “high profile litigator,” a “Hollywood Power Lawyer,” and a “celebrity power attorney.”

Additionally, Mathew was recently described by his client Sean Penn in a New York Times article as a “tough as nails streetfighter with a big brain and bigger principles” and by his former Justice Department supervisor and now United States District Judge Robert J. Conrad as “one of the sharpest lawyers I’ve ever met at the Department of Justice,” whose “judgment is impeccable.”

Among many other cases, Mathew won a defamation lawsuit for Sean Penn; a $6 million “cutting rights” case for Academy Award winner Kenneth Lonergan regarding his film “Margaret” starring Matt Damon; a multi-year $20 million arbitration for his client Credit Suisse against billionaire Ronald Lauder and 11 other claimants; and a $14 million trial verdict in a New York trial (on a counterclaim) after extensive bi-coastal litigation for his hedge fund client Sandton Capital against a film production company. Mathew also recently served as lead counsel for Fortune 20 company Verizon in one of the largest False Claims Act cases in the country, involving more than $500 million in claims. 

Mathew has recently twice been recognized in The American Lawyer’s “Litigator of the Week” column, for going from “defense-to-offense” for NBA superstar Jimmy Butler in a case involving Mathew’s innovative use of the California Talent Agency Act and after obtaining the suspension of Britney Spears’s father as conservator of her Estate. In addition to complex commercial litigation, Mathew has perennially been recognized as one of the nation’s leading entertainment litigators by both The Hollywood Reporter in its “Power Lawyer Report” (listing the industry’s Top-100 most influential attorneys) and Variety (in its “Legal Impact Report,” spotlighting the world's leading attorneys in the entertainment industry). Mathew also received Variety’s prestigious 2022 Power of Law Award, which was presented to him by Sean Penn.


  • Litigation
  • Media and entertainment litigation
  • White collar criminal defense



  • Law Clerk to Justice David H. Souter, Supreme Court of New Hampshire
  • Trial Attorney, Civil and Criminal Divisions of the United States Department of Justice 
  • Supervisory Assistant United States Attorney, United States Department of Justice 
  • Senior Associate Independent Counsel/Supervisory Assistant United States Attorney, Office of Independent Counsel 
  • Trial Attorney, United States Department of Justice, Criminal Division Campaign Finance Task Force

Recognition & Leadership

  • Listed, Daily Journal
    • California Lawyer Attorney of the Year, 2022
    • Top 100 Lawyers (listing the Top 100 lawyers in the State)
  • Listed, Los Angeles Business Journal
    • "Top 100 Lawyers List," 2022
    • “Leaders of Influence: Litigators & Trial Attorneys,” 2021-2022 (Recognizing Los Angeles’s Top Litigators and “Masters Of Their Craft”)
    • LA500 List of Visionary Leaders
  • Listed, The National Law Journal, Sports & Entertainment Law Trailblazer
  • Listed, The American Lawyer, Litigator of the Week and “Shout Out,” Litigator of the Week
  • Listed, Billboard magazine, "Top Music Lawyers," 2022
  • Listed, Variety, "Legal Impact Report," 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022
  • Listed, The Hollywood Reporter, "Power Lawyers: Top 100 Most Influential Entertainment Lawyers in America," 2014, 2015, 20162017, 2021, 2022
  • Lawyer of the Year, Above the Law
  • Recipient, Variety, Power of Law Award, 2022
  • Lawyer of the Week, Judicial Notice/Original Jurisdiction
  • Named one of California's Top 100 Trial Lawyers, The National Trial Lawyers
  • Featured, Los Angeles Confidential Magazine, "Power Player"
  • Special Achievement Award for Meritorious Acts of Service, United States Department of Justice
  • Federal Bar Association’s Younger Lawyer Award – Awarded by Panel of Federal Judges to the Top 5 government litigators under age 36
  • Special Act Awards for Outstanding Performance, United States Department of Justice
  • Commendation, federal prosecution and conviction of defendant in United States v. Sheffield, United States Department of Justice, Bureau of Alcohol Tobacco & Firearms, Internal Affairs
  • Commendation, federal prosecution and conviction of defendant in United States v. Brisbane, United States Department of Justice
  • Board of Governors, Beverly Hills Bar Association, 2020 
  • Adjunct Professor of Law, "Criminal Procedure: Grand Jury Law & Practice," Fordham Law School, 2004-2006 
  • Adjunct Professor of Law, "White Collar Crime," Pepperdine University School of Law, 2007 
  • Faculty, United States Attorney General's National Advocacy Center, lecturing in Trial Practice, 2000
  • Dean's Advisory Council, Tulane University
  • Member, Association of Business Trial Lawyers Los Angeles


  • J.D., cum laude, Boston College Law School
  • B.A., Tulane University
  • California
  • New York
  • U.S. District Court for the Southern District of New York
  • U.S. District Court for the Eastern District of New York
  • U.S. District Court for the Central District of California